Missile guidance command limitation system for dynamic controllability criteria

Abstract

A method and system for limiting missile guidance correction within the physical control capabilities of the missile, while fully utilizing missile maneuver and control capabilities. The method and system of the present invention are applied through missile guidance control electronics. First, a dynamic rate limit is calculated to prevent aerodynamic trim limit overshoot, which is directly related to body attitude rate. Second, a dynamic angle of attack limit is calculated to control aerodynamic trim limit based on thrust deflection and/or aerodynamic control surface deflection. Third, a dynamic angular acceleration limit is calculated to balance control moments produced by mechanisms such as thrust deflection and/or aerodynamic control surface deflection with vehicle moments of inertia. Fourth, the dynamic limit on rate of change of angular acceleration is set to maintain control system margins in terms of maximum enforceable moment in excess of the trim moment at the current angle of attack and maximum slew rate of the thrust deflector.

Claims

1. A method of guiding a missile to an intended target, comprising the steps of:

providing missile guidance electronics;

storing a plurality of algorithms for computing missile guidance commands, said commands being selectively activated by said missile guidance control electronics;

prior to applying said missile guidance commands, using said missile guidance control electronics to generate a plurality of dynamic control limiting commands including:

commands limiting missile body rate to ensure a projected trim margin to thereby prevent said missile from overshooting its angle of attack trim capability; and

commands limiting missile angular acceleration to that which is dynamically achievable by said missile; and

applying said plurality of dynamic control limiting commands to said missile guidance commands to produce a plurality of dynamically limited commands which are adapted to control said missile within physical parameters achievable by said missile.

2. The method of claim 1, wherein said step of generating a plurality of dynamic control limiting commands comprises the step of generating a missile control limiting command that limits missile body rate.

3. The method of claim 1, wherein said step of generating a plurality of dynamic control limiting commands comprises the step of generating a command that limits missile instantaneous angle of attack.

4. The method of claim 1, further comprising the steps of:

providing missile navigation electronics for determining missile navigation data; and

transmitting said missile navigation data from said missile navigational electronics to said missile guidance electronics to update said missile guidance electronics on missile flight path and position.

5. A missile system, comprising:

a missile; and

missile control electronics, comprising:

a memory programmed with a plurality of missile guidance commands and a plurality of missile guidance correction commands for controlling guidance of said missile to its intended target, said memory also being programmed with a plurality of missile guidance correction limit computations limiting operation of said missile guidance correction commands within capability parameters determined in real time;

a processor for selectively activating said plurality of missile guidance commands and said plurality of missile guidance correction commands and, subsequent to activation of said missile guidance correction commands, activating said plurality of missile guidance correction limit computations in response to dynamically sensed missile flight data to output guidance commands to guide said missile to said intended target;

said plurality of missile guidance correction limit computations including:

computations to limit missile body rate to ensure a projected trim margin for said missile;

computations to limit missile angular acceleration to that which is dynamically achievable by said missile;

computations to limit an angle of attack of said missile to said missile trim limit; and

computations to limit missile rate of change in angular acceleration; and

missile guidance means for adjusting flight of said missile in response to said guidance commands output from said processor.

6. The system of claim 5, wherein said plurality of missile guidance correction limit computations comprises a command that limits missile body rate.

7. The system of claim 5, wherein said plurality of missile guidance correction limit computations comprises a command that limits missile instantaneous angle of attack.

8. The system of claim 5, wherein said plurality of missile guidance correction limit computations comprises a command that limits missile angular acceleration.

9. The system of claim 5, wherein said plurality of missile guidance correction limit computations comprises a command that limits missile rate of change of angular acceleration.

10. The system of claim 5, wherein said processor cycles through said limit commands at approximately 20-60 cycles per second to provide said limit commands in real time to said missile guidance means.